Progressing cavity pump with heat management system

ABSTRACT

A progressing cavity pump heat management system including a progressing cavity pump and a controller. The controller is configured to receive data relating to the temperature of materials exiting the pump and the differential pressure across the pump to determine whether corrective action is required. The controller is configured such that if the controller determines that corrective action is required, the controller institutes corrective action to seek to reduce at least one of the temperature of materials exiting the pump or differential pressure across the pump.

This application claims priority to U.S. Provisional Application Ser.No. 60/955,914, filed on Aug. 15, 2007, the entire contents of which arehereby incorporated by reference.

The present invention is directed to a progressing cavity pump, and moreparticularly, to a progressing cavity pump with a heat managementsystem.

BACKGROUND

A fluid/material consisting of more than one phase is typically termed amulti-phase fluid/material. For example, a fluid/material which is acombination of gas and liquid is typically called a two phasefluid/material, and a fluid/material which is a combination of gas,solid, and liquid may be called a tri phase fluid/material. Whenmaterials are pumped by a progressing cavity pump, liquids, liquid vaporand certain solids in the pumped material may help to lubricate therotor/stator interface in the pump and provide heat dissipation.However, when pumping two phase, tri phase, or multi-phase materials, arelatively high presence of gas can lead to a lack of sufficientlubrication and/or lack of heat dissipation in the pump, which can causeoverheating and damage, particularly to the elastomer material of thepump.

SUMMARY

Accordingly, in one embodiment the present invention is a system inwhich certain parameters are monitored to determine the status of thepump such that corrective action can be instituted, if necessary. In oneembodiment, the invention is a progressing cavity pump heat managementsystem including a progressing cavity pump and a controller. Thecontroller is configured to receive data relating to the temperature ofmaterials exiting the pump and the differential pressure across the pumpto determine whether corrective action is required. The controller isconfigured such that if the controller determines that corrective actionis required, the controller institutes corrective action to seek toreduce at least one of the temperature of materials exiting the pump ordifferential pressure across the pump.

In another embodiment the invention is a method for pumping materialsincluding the steps of pumping materials through a progressing cavitypump, monitoring a temperature of materials exiting the pump, andmonitoring a differential pressure across the pump. The method furtherincludes the step of instituting corrective action if it is determinedthat corrective action is required based at least in part upon themonitored pressure and differential pressure.

In yet another embodiment, the invention is a method for pumpingmaterials including the step of providing a progressing cavity pumpoperatively coupled to a wellhead such that the pump is configured topump materials provided from the wellhead. The method further includesthe step of operating the pump such that the pump pumps materialconstituting at least 80% gas by volume therethrough for at least twominutes without significant damage to the pump.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective, partial cutaway view of a progressing cavitypump with a heat management system; and

FIG. 2 is a flow chart illustrating one method for implementing a heatmanagement system.

DETAILED DESCRIPTION

As shown in FIG. 1, a progressing cavity pump 10 may include a generallycylindrical stator tube 12 having a stator 14 located therein. Thestator 14 has an opening or internal bore 16 extending generally axiallyor longitudinally therethrough in the form of a double lead helical nutto provide an internally threaded stator 14. The pump 10 includes anexternally threaded rotor 18 in the form of a single lead helical screwrotationally received inside stator 14. The rotor 18 may include asingle external helical lobe 20, with the pitch of the lobe 20 beingtwice the pitch of the internal helical grooves of the stator 14.

The rotor 18 fits within the stator bore 16 to provide a series ofhelical seal lines 22 where the rotor 18 and stator 14 contact eachother or come in close proximity to each other. In particular, theexternal helical lobe 20 of the rotor 18 and the internal helicalgrooves of the stator 14 define the plurality of cavities 24therebetween. The stator 14 has an inner surface 26 which the rotor 18contacts or nearly contacts to create the cavities 24. Particularly whenthe rotor 18 and/or the stator 14 is an elastomer material the rotor 18and the inner surface 26 of the stator 14 may form an interference fittherebetween to define the cavities 24.

The rotor 18 is rotationally coupled to a drive shaft 30 by a pair ofgear joints 32, 34 and by a connecting rod 36. The drive shaft 30 isrotationally coupled to a motor 38. When the motor 38 rotates the driveshaft 30, the rotor 18 is rotated about its central axis and thuseccentrically rotates within the stator 14. As the rotor 18 turns withinthe stator 14, the cavities 24 progress from an inlet or suction end 40of the rotor/stator pair to an outlet or discharge end 42 of therotor/stator pair. The pump 10 includes a suction chamber 44 in fluidcommunication with the inlet end 40 into which fluids to be pumped maybe introduced. During a single 360° revolution of the rotor 18, one setof cavities 24 is opened or created at the inlet end 40 at exactly thesame rate that a second set of cavities 24 is closing or terminating atthe outlet end 42 which results in a predictable, pulsationless flow ofpumped material.

The pitch length of the stator 14 may be twice that of the rotor 18, andthe present embodiment illustrates a rotor/stator assembly combinationknown as 1:2 profile elements, which means the rotor 18 has a singlelead and the stator 14 has two leads. However, the present invention canalso be used with any of a variety of rotor/stator configurations,including more complex progressing cavity pumps such as 9:10 designswhere the rotor has nine leads and the stator has ten leads. In general,nearly any combination of leads may be used so long as the stator 14 hasone more lead than the rotor 18. Progressing cavity pumps are discussedin greater detail in U.S. Pat. Nos. 2,512,764, 2,612,845, 5,722,820,6,120,267 and 6,491,591, the entire contents of which are incorporatedherein by reference.

The stator 14 can be made of any of a variety of materials, but may bemade of a material that is also chemically inert and wear resistant. Forexample, the stator 14 may be made of elastomers, nitrile rubber,natural rubber, synthetic rubber, fluoroelastomer rubber, urethane,ethylene-propylene-diene monomer (“EPDM”) rubber, polyolefin resins,perfluoroelastomer, hydrogenated nitriles and hydrogenated nitrilerubbers, polyurethane, epichlorohydrin polymers, thermoplastic polymers,polytetrafluoroethylene (“PTFE”), polychloroprene (such as neoprene),synthetic rubber or rubber compositions, such as VITON® materials soldby E.I. du Pont de Nemours and Company located in Wilmington Del.,synthetic elastomers such as HYPALON® polyolefin resins and syntheticelastomers sold by E.I. du Pont de Nemours and Company, synthetic rubbersuch as KALREZ® synthetic rubber sold by E.I. du Pont de Nemours andCompany, tetrafluoroethylene/propylene copolymer such as AFLAS®tetrafluoroethylene/propylene copolymer sold by Asahi Glass Co., Ltd. ofTokyo, Japan, acid-olefin interpolymers such as CHEMROZ® acid-olefininterpolymers sold by Chemfax, Incorporated of Gulfport Mississippi, andvarious other materials.

The suction chamber 44 of the pump 10 may be directly coupled to a twophase, multi-phase or tri phase source such as a well or wellheadthrough which down-hole materials including liquids, solids and gasesare raised/pumped. In this case the pump 10 may be positioned on theground surface but at or adjacent to a well, wellhead, or down-well pump(or other fluid source). Reducing and maintaining well head pressure bythe pump 10 will result in higher liquid production flow rates by boththe pump 10 and the wellhead. Thus, during normal operation the pump 10(along with other pumps or components in the system) may be controlledsuch that the well head pressure is maintained at a constant value. Therotational speed of the rotor 18 may be varied as desired in order tomaintain this constant pressure.

As briefly noted above, the presence of fluids, fluid vapors and/orcertain malleable solids in the pumped materials help to lubricate thejunction between the rotor 18 and stator 14 (i.e. along the seal lines22) and also help to dissipate heat that may be generated duringoperation due to the interference fit between the rotor 18/stator 14,and compression of the gas subject to the ideal gas law. If gas ispresent in the pumped materials, lubricating and cooling effects arereduced or lost. If the friction/heat build up becomes too high (i.e. inone case, if the gas constitutes over by 95% of the pumped materials byvolume) the pump 10, and particularly any elastomer or similar materialsof the rotor 18 and/or stator 14, can be damaged. This phenomemon can beparticularly prominent when the pump 10 is used in an oil field or otherwellhead or down-hole applications. In these cases pockets of gas, suchas natural gas, may be introduced into the pump 10 which can cause thepump to run in a “dry” state.

In order to address this type situation the pump 10 may include or beintegrated into a heat management system, generally designated 46. Theheat management system 46 may include or implement the tracking ofcertain parameters and the institution of protective measures to reduceheat and temperatures in the pump 10. In one embodiment the measuredparameters are: 1) the temperature of the materials exiting the pump 10at the outlet end 42; 2) the inlet or suction pressure of the pump 10(i.e. pressure at the suction end 40/suction chamber 44; and 3) theoutlet pressure of the pump 10 (i.e. pressure at the outlet end 42).

As can be seen in FIG. 1, the pump 10 may include a dischargetemperature sensor 48 to sense the temperature of the materials exitingthe pump 10, an inlet pressure sensor 50 to sense the pressure of thematerials entering the pump 10, and a discharge pressure sensor 52 tosense the pressure of the materials exiting the pump 10. The sensors 48,50, 52 are operatively coupled to a controller 54, such as aprogrammable logic controller, processor, computer, chip, logic, CPU orthe like (hereinafter termed a controller to thereby include all ofthese terms listed above). In this manner data relating to the sensedpressures and discharge temperature are fed to the controller 54.

In order to determine whether corrective action is required, thecontroller 54 calculates and tracks pressure drop across the pump 10.The pressure drop value (ΔP) is the difference between the inletpressure, sensed by sensor 50, and outlet pressure, sensed by the sensor52. The controller 54 may also track the outlet temperature andcalculate and track a composite value of the outlet temperature and ΔP,or a composite value incorporating the outlet temperature and ΔP. Whenthe sensed properties and/or composite value exceed certain thresholdvalues, corrective action may be taken.

For example the controller 54 may have algorithm stored or runningthereon that determines that corrective action is required when: 1) theΔP exceeds a certain level; and/or 2) the discharge temperature exceedsa certain level; and/or 3) the composite value incorporating ΔP anddischarge temperature exceeds a certain value. The control algorithm canalso take into account trends and time-variable statistics to detecttroublesome increases in ΔP and/or discharge temperature, and/or thecomposite values.

The composite value may be calculated in a variety of manners. By way ofexample, the composite value can be determined by calculating theaverage increase in ΔP over a discrete period of time, calculating theaverage increase in discharge temperature over discrete period of time,and multiplying those values together.

The ultimate physical quantity to be tracked can be considered to be thetemperature of the stator 14 and/or rotor 18. Since the stator 14 and/orrotor 18 can be made of an elastomer material, the stator 14 and/orrotor 18 may be the first component of the pump 10 to be damaged by hightemperatures. However, it can be difficult and expensive to directlymeasure the temperature of the stator 14 and/or rotor 18. Thus, bymeasuring ΔP and discharge temperature, the present system and methodcan provide an efficient method to inductively determine the temperatureof the stator 14 and/or rotor 18.

A high ΔP means that relatively high amount of energy is being impartedto the stator 14 and/or rotor 18. However, an elastomer stator 14 and/orrotor 18 is typically of a relatively thermally insulating material, soan elastomer stator 14 and/or rotor 18 may be relatively warm, even ifthe materials exiting the pump 10 are not. Thus it may be important tomeasure not just the outlet temperature, but also the ΔP.

FIG. 2 illustrates a flow chart including various steps that may beimplemented to track heat build up and take corrective steps. At thefirst step 60 of FIG. 2 ΔP and the outlet temperature are measured. Atstep 62, those properties and/or the composite value(s) are compared toinitial thresholds. The thresholds tracked by the controller 52 willvary widely and depend upon, among other factors, the materials to bepumped, the nature and materials of the pump 10 (particularly thematerials of the stator 14 and/or rotor 18, such as the upper thermallimits of those components), ambient pressures and temperatures,incoming temperature and pressure of the material to be pumped, andother variables. However, in one illustrative embodiment the initialthreshold for ΔP is about 10 psi and the initial threshold for dischargetemperature is about 120° F. The initial threshold for the compositevalue will vary, depending upon how it is determined.

At step 64, it is determined whether the initial thresholds areexceeded, thereby determining whether initial corrective action isrequired. If initial corrective action is needed, then the systemproceeds to step 66 wherein the initial corrective action isimplemented. The initial corrective action can be implemented in avariety of manners and can take any of a variety of forms, includingslowing the pump 10, introducing liquid into the pump 10, activelycooling the pump 10, or combinations of these features. In oneembodiment, in order to institute the initial corrective action thecontroller 52 sends a signal to the motor 38 which causes the motor 38and pump 10 to slow down (i.e. the rate of rotation of the rotor 18 isreduced), which reduces heat build-up. The pump 10 can be slowed down asdesired, but in one embodiment is slowed down by about 10%. Thisslow-down will typically increase the wellhead pressure above theconstant pressure desired to be maintained on the wellhead, but may be anecessary step to avoid damage to the pump 10.

If the incoming temperature of the material to be pumped is relativelyhigh, then the initial corrective action may need to be institutedfairly quickly. On the other hand, if the incoming temperature of thematerial to be pumped is relatively low, a time lag may be institutedbefore the initial corrective action (i.e. slowing of the pump 10) isimplemented, which allows the pump 10 to operate at higher efficienciesfor longer periods of time. This time lag could also be implemented aspart of the other corrective actions described below.

During the initial corrective action, discharge temperature and ΔP arecontinued to be measured and compared to the initial threshold values(and/or other interim values, if desired) by the controller 54 at step68. If the initial corrective action succeeds in sufficiently loweringthe parameters below the desired limits, the initial corrective actionmay be terminated at step 70 (i.e. the pump 10 may be allowed to returnto its previous set point speed) and the system returns to step 60.

At step 72, it is determined whether the parameters exceed secondary(typically higher) thresholds. For example, in one illustrative examplethe secondary ΔP threshold value is about 15 psi and the secondtemperature threshold value is about 130° F. If at step 70 it isdetermined that the secondary threshold values are exceeded, secondarycorrective action is instituted at step 74; otherwise initial correctiveaction is continued at step 66. The secondary corrective action at step74 can take any of a variety of forms, including further slowing thepump 10, introducing liquid into the pump, actively cooling the pump, orcombinations of these features.

In the illustrative example explained herein the secondary correctiveaction 74 includes introducing fluid into the pump 10. For example, asshown in FIG. 1, a fluid reservoir 84 may be fluidly coupled at oradjacent to the inlet 44 of the pump 10. When secondary correctiveaction is required a pump is operated, and/or a valve 86 is opened bythe controller 54 such that fluid 88 in the reservoir 84 is introducedinto the pump 10. The introduced fluid 88 immediately cools the pump 10by providing lubrication and heat dissipation. The secondary correctiveaction may be instituted while the initial corrective action is alsooccurring; or the initial corrective action may be suspended while thesecondary corrective action is implemented.

The fluid 88 can be nearly any fluid, such as water, oil, fluids beingpumped by the pump 10, or the like. The amount of fluid introduced intothe pump 10 can vary, but may constitute, for example, between about 1%and about 10% by volume of the materials being pumped.

FIG. 1 illustrates the fluid 88 being introduced at the inlet 44 of thepump 10. However, the fluid 88 may also be introduced at downstreamareas of the pump 10. For example, the most effective cooling may beobtained by introducing fluid at the point just upstream of the point ofhighest heat due to compression (i.e., depending upon the situation,about halfway along the stator 14, or about ¾ or more down the length ofthe stator 14). This method of introducing fluid may provide moreeffective cooling but may also require that another port be formed inthe pump 10/stator 14.

After the secondary corrective action is implemented at step 74, at step76, it is determined whether the secondary thresholds (and/or otherinterim values, if desired) are exceeded. If they are not, at step 78the secondary corrective action is terminated, and the initialcorrective action is instituted/continued at step 66. On the other hand,if, at step 76, it is determined that the secondary thresholds areexceeded, the measured parameters are compared to tertiary thresholds atstep 80. In the illustrative example the tertiary values are higher thanthe initial and secondary thresholds (i.e. about 20 psi and about 140°F. in one embodiment).

If the tertiary thresholds are not exceeded, the secondary correctiveaction, at step 74, is continued. Conversely, if the tertiary thresholdsare exceeded, the system proceeds to step 82 wherein tertiary correctiveaction is implemented. The tertiary corrective action can take a varietyof forms, but in the illustrative example the tertiary corrective actiontakes the form of shutting down the pump 10 to prevent further damage.Of course, rather than shutting down the pump, other corrective actionmay be utilized, and quaternary thresholds and corrective action, etc.,may be instituted as desired.

The heat management system described herein is effective in providingquick and efficient cooling and corrective action to a potentiallyoverheating pump 10. In fact, the heat management system is so effectivethat the pump 10 may be used to pump gases, such as natural gas, as upto 100% of the pumped materials (or material entering the pump 10). Thusin addition to being used and/or positioned to pump fluids, two phasematerials, tri phase materials or multi-phase materials, the pump 10 canbe designed, used and/or positioned to pump gas, such as natural gas.This represents a significant change from conventional use ofprogressing cavity pumps which are not typically used to pump gases.

Moreover, the use of the pump 10 in conjunction with a down-hole pumpallows the pump 10 to transport pumped fluids away from the well orwell-head for subsequent processing (i.e. separation or the like). Theuse of the pump 10 in this manner reduces demands placed on thedown-hole pump (i.e. reducing well-head pressure) which can prolong thelife of the down-hole pump and/or allow a smaller and more inexpensivedown-hole pump to be used and/or provide a higher production liquid flowrate.

In one embodiment the pump 10 may be able to continuously pump at leastabout 60%, or alternately at least about 80%, further alternately up to95% or even further alternately up to 100%, gas by volume (as eitherpumped material or incoming material) or more for up to two minutes, oralternately up to four minutes, or further alternately up to 30 minutesor more without significant damage to the pump (i.e., the rotor 18 andstator 14 remain intact, without damage, melting, pitting, etc., whichcauses permanent damage requiring repair, and/or effects the performanceof the pump). These levels of operation allow a pump 10 to be used inareas in which pockets of gas are present within expected ranges. Inthis manner, the pump 10 can be used to de-water drilling sites, andalso pump materials (such as natural gas) after the de-watering iscompleted without having to switch pumps.

Having described the invention in detail and by reference to thepreferred embodiments, it will be apparent that modifications andvariations thereof are possible without departing from the scope of theinvention.

1. A progressing cavity pump heat management system comprising: aprogressing cavity pump; and a controller configured to receive datarelating to the temperature of materials exiting the pump and thedifferential pressure across the pump to determine whether correctiveaction is required, and wherein said controller is configured such thatif the controller determines that corrective action is required, saidcontroller institutes corrective action to seek to reduce at least oneof the temperature of materials exiting the pump or differentialpressure across the pump.
 2. The system of claim 1 further comprising atemperature sensor configured to measure the temperature of materialsexiting the pump, a discharge pressure sensor configured to measure thepressure of material exiting the pump, and an inlet pressure sensorconfigured to measure the pressure of material entering the pump,wherein said temperature sensor, said discharge pressure sensor, andsaid inlet pressure sensor are operatively coupled to said controllersuch that said controller can thereby receive data relating to thetemperature of materials exiting the pump and the differential pressureacross the pump.
 3. The system of claim 1 wherein said corrective actionincludes at least one of reducing the speed of said pump or introducingfluid into said pump.
 4. The system of claim 1 wherein said controlleris configured to calculate a single composite value based upon saidtemperature and said differential pressure, and wherein said compositevalue is used by said controller to determine whether corrective actionis required.
 5. The system of claim 1 wherein said controller determinesthat corrective action is required if said temperature and saiddifferential pressure, or a composite value thereof, exceeds apredetermined threshold or thresholds.
 6. The system of claim 1 whereinsaid corrective action is instituted to cool a stator of the progressingcavity pump.
 7. The system of claim 1 wherein said controller isconfigured to compare said temperature and said differential pressure,or a composite value thereof, to an initial threshold or thresholds, andif such initial threshold or thresholds are exceeded, to institute afirst corrective action which seeks to reduce at least one of thetemperature of materials exiting the pump or the differential pressureacross the pump, and wherein said controller is configured to comparesaid temperature and said differential pressure, or a composite valuethereof, to a secondary threshold or thresholds, and if such secondarythreshold or thresholds are exceeded, to institute a second correctiveaction which seeks to reduce at least one of the temperature ofmaterials exiting the pump or the differential pressure across the pumpand which differs from said first corrective action.
 8. The system ofclaim 7 wherein said secondary threshold or thresholds are surpassedwhen at least one of said temperature, said differential pressure, orsaid composite value is higher than is required to surpass said initialthreshold or thresholds.
 9. The system of claim 8 wherein saidcontroller is configured to compare said temperature and saiddifferential pressure, or a composite value thereof, to a tertiarythreshold or thresholds, and if such tertiary threshold or thresholdsare exceeded, to institute a tertiary corrective action which differsfrom said primary and secondary corrective action, and wherein saidtertiary threshold or thresholds are surpassed when at least one of saidtemperature, said differential pressure, or said composite value ishigher than is required to surpass said initial threshold or thresholdsor said secondary threshold or thresholds.
 10. The system of claim 9wherein said tertiary corrective action constitutes ceasing pumpingoperations of said pump.
 11. The system of claim 1 wherein saidprogressing cavity pump includes a rotor, a stator, an inlet and anoutlet, said rotor being rotationally disposed in said stator such thatrotation of said rotor causes material in said pump to be pumped fromsaid inlet toward said outlet.
 12. The system of claim 11 wherein saidrotor is an externally threaded rotor in the form of a single leadhelical screw, and wherein said stator has an opening extendinggenerally axially therethrough in the form of a double lead helical nut,and wherein said rotor is received in said opening.
 13. The system ofclaim 11 wherein said stator is made of an elastomer material.
 14. Thesystem of claim 1 wherein said pump is coupled to a wellhead to receivematerials pumped therefrom.
 15. A method for pumping materialscomprising the steps of: pumping materials through a progressing cavitypump; monitoring a temperature of materials exiting the pump; monitoringa differential pressure across the pump; and instituting correctiveaction if it is determined that corrective action is required based atleast in part upon the monitored pressure and differential pressure. 16.The method of claim 15 wherein the corrective action is instituted ifsaid temperature and said differential pressure, or a composite valuethereof, exceeds a predetermined threshold or thresholds, and whereinsaid corrective action leads to cooling of the progressing cavity pump.17. The method of claim 15 wherein said corrective action includes atleast one of reducing the speed of said pump, or introducing fluid intosaid pump, or ceasing pumping operations of said pump.
 18. A method forpumping materials comprising the steps of: providing a progressingcavity pump operatively coupled to a wellhead such that said pump isconfigured to pump materials provided from said wellhead; and operatingsaid pump while actively reducing at least one of the temperature ofmaterials exiting the pump or the differential pressure across the pumpduring at least part of said operation such that the pump pumps materialconstituting at least 80% gas by volume therethrough for at least twominutes without significant damage to the pump.
 19. The method of claim18 wherein said operating step includes monitoring the temperature ofmaterials exiting the pump, monitoring the differential pressure acrossthe pump, and instituting corrective action to cool the pump if it isdetermined that corrective action is required based upon the monitoredpressure and differential pressure.
 20. The method of claim 19 whereinthe corrective action is required if said temperature and saiddifferential pressure, or a composite value thereof, exceeds apredetermined threshold or thresholds, and wherein said correctiveaction includes at least one of reducing the speed of said pump orintroducing fluid into said pump.
 21. The system of claim 1 wherein saiddifferential pressure is a pressure differential between an inlet ofsaid pump and an outlet of said pump.
 22. The system of claim 1 whereinsaid progressing cavity pump includes a rotor, a stator, an inlet and anoutlet, said rotor being rotationally disposed in said stator such thatrotation of said rotor causes material in said pump to be pumped fromsaid inlet toward said outlet, and wherein said differential pressure isa pressure differential between an inlet of said pump located at aposition upstream of said rotor and an outlet of said pump located at aposition downstream of said rotor and in fluid communication with saidinlet.
 23. The system of claim 1 wherein said progressing cavity pumpincludes a rotor, a stator, an inlet and an outlet, said rotor beingrotationally disposed in said stator such that rotation of said rotorcauses material in said pump to be pumped from said inlet toward saidoutlet, and wherein said data relating to the temperature of materialsexiting the pump is data relating to the temperature of material atposition downstream of said rotor.
 24. The system of claim 2 whereinsaid controller is configured to institute corrective action if thedifferential pressure exceeds a predetermined value.
 25. The system ofclaim 1 wherein said controller is configured to take into considerationboth: a) data relating to the temperature of said materials exiting thepump; and b) the differential pressure across the pump in determiningwhether corrective action is required.
 26. A progressing cavity pumpheat management system comprising: a controller configured to receivedata relating to the temperature of materials exiting a progressingcavity pump and the differential pressure across the pump to determinewhether corrective action is required, and wherein said controller isconfigured such that if the controller determines that corrective actionis required, said controller institutes corrective action to seek toreduce at least one of the temperature of materials exiting the pump ordifferential pressure across the pump.